Elevations and/or depressions on bottle surfaces can occur e.g. at molding seams and relief-like impressions at the bottle body, the so-called embossings.
Bottles with a molding seam, such as bottles for beverages, must be preferably labeled such that the molding seam is not covered by the label. Furthermore, the label is possibly to be oriented with respect to an embossing. To detect the position of a molding seam or an embossing and permit later rotation of the bottle to a desired position, it is known to examine a lamp reflection formed on the bottle body for irregularities in various rotational positions of the bottle. In the process, normally only a portion of the molding seam or the embossing, respectively, can be detected by the lamp reflection.
DE 10 2004 040 164 A1, for example, describes a semicircular, uniformly illuminated lamp shade arranged coaxially around the axis of symmetry of a bottle to be examined and comprising an aperture through which the surface of the bottle is examined for irregular reflections by means of a camera. In case of profiled bottle surfaces, however, the edges of the light reflections can have an irregular shape and be difficult to detect exactly in a low-contrast representation. Furthermore, the molding seam might only be represented in a small area at the edge of the light reflection. With the known technique, the molding seam is therefore not always reliably detected.
Embossings are preferably arranged in the area of the shoulder of the bottle. In the usual horizontal viewing direction of the camera, the embossing is then often located outside of the lamp reflection. Therefore, comparably low-contrast, irregular reflections are formed at the embossing the shape of which changes while the bottle is rotated.
Due to these problems, a check measurement with an additional fine adjustment of the bottle is required. This requires an additional inspection device and much space in the labeling machine which is not desired.